Alcohol-fuelled mayhem caused up to £30,000 worth of damage to a family home after around 800 teenagers gatecrashed a schoolgirl’s party after she advertised it on Facebook.

A piano was smashed up in the front garden in astonishing scenes of carnage in and around the three-bedroom house in Billericay, Essex.

Elsewhere in the house foul language was written on walls, furniture was overturned and smashed while doors were ripped from their hinges by hordes of youngsters who gatecrashed the party.

The party was thrown by Sarah Hine, 14, but got out of control despite her mother, Esther, 56, being there to try and keep order.

Mrs Hine said: ‘There must be £20,000 to £30,000 damage but insurance won’t pay out because we invited them in. I told the parents I would be here to keep an eye out for trouble.’

Witnesses at the party claimed teenagers had broken into the loft and were bouncing on ceiling insulation before one fell through into the bedroom. The wild partygoers also destroyed a piano outside the front of the house.

The family’s bedrooms were ripped to pieces, as furniture was pulled apart and thrown about the room and walls were daubed with vulgar sexual messages.

The party had been dubbed the ‘Project X of Essex’ in reference to American blockbuster Project X in which three High School students plan a giant house party to make a name for themselves, with massive consequences.

Partygoers continued to spread the word about the Friday night party on Facebook and Twitter, even as it spiralled out of control.

Terrified and angry neighbours called the police, who arrived around 9pm to disperse the unruly crowd.

One neighbour, who declined to be named, said: ‘It was like Belfast in the 1970s out there. It was

terrifying to see it in the quiet road. There were hundreds of people out to cause trouble.’

Another said: ‘I would have said there was about 800 of them when the police turned up at around 8.30pm

‘They were trying to escape up the road not realising it was a cul-de-sac.

‘We’ve never seen anything like this before as it’s usually a very quiet road.’

Police reported no injuries to partygoers at the gathering, which had been planned by Sarah as an early birthday celebration ahead of her birthday in the New Year.

Mrs Hine added: ‘I am stunned – why would they do this?

‘There wasn’t supposed to be drink but the police told me they confiscated an unbelievable amount of alcohol from the groups.’

Mrs Hine revealed she had ignored warnings made two weeks ago that the party could get out of hand when staff at her daughter’s school saw an open invitation to the event had appeared on Facebook

She added: ‘I just didn’t think this would happen. I knew Sarah knew some people but did not expect that many to turn up.’

Despite the carnage, Mrs Hine, who works for her husband’s computer consultancy business, has said she will not ground her daughter.

A spokesperson for Sarah’s school, the Anglo European School in Ingatestone, Essex, said: ‘We were saddened to hear about the damage caused to one of our pupil’s homes this weekend following a party which got out of control.

‘We were aware that the party was being advertised on Facebook and advised the mother and daughter of the risks this posed.

‘We regularly speak with our students about the dangers of social media and while young people from across Essex attended the event we hope our students will learn lessons from this incident.’

An Essex Police spokesman confirmed police had attended a house in Billericay, Essex, on Friday night to disperse a large number of teenagers.

She continued: ‘Police were called after calls from residents regarding nuisance behaviour in the street.

‘Officers found a large number of teenagers had visited the area to attend a party advertised openly on social media.

‘No arrests were made and no complaints were made regarding criminal damage.

‘However, police cleared the area and assisted with the dispersal of the teenagers and their safe travel home via Billericay rail station.’

Last week it was reported that more than 1,000 revellers, including Britain’s Got Talent judge Alesha Dixon, packed into the home of the parents of Ollie Boorman in the village of Tewin, Hertfordshire, after he posted it on Facebook.

The party was called Project XXX and strangers from as far afield as Manchester turned up. Boorman pleaded guilty to public nuisance and was given a community order and ordered to pay £500 compensation to Hertfordshire Police and £85 costs.